1. Background of the Invention
The present invention relates to a tool linkage device for a robot hand. In particular, the present invention relates to a robot hand tool linkage device in which a plurality of radially provided rod members act as joining members for a locking mechanism which reliably connects a master plate and a tool plate.
2. Description of the Related Art
A robot hand tool linkage device selectively attaches and detaches several types of tools from a hand output part of a robot hand. Generally, robot hand tool linkage devices have an inner assembly (master plate) that is attached to a hand output part of a robot hand, an outer assembly (tool plate) onto which a tool is attached, and a locking mechanism which locks the inner assembly and outer assembly.
U. S. Pat. No. 4,696,524 discloses a robot hand tool linkage device that can rapidly connect and disconnect an inner assembly and an outer assembly. The locking mechanism for this robot hand tool linkage device has a piston member, a plurality of ball members acting as the joining members, and a ball receiver as a latching part.
The piston member is supported by the inner assembly and is slidable from a lock position to a lock release position. The ball member is housed and retained in a housing hole of an approximately cylindrical ball retainer which surrounds the outer perimeter of the output part of the piston member connected to the inner assembly.
The ball member can move in a direction which is perpendicular to the sliding direction of the piston member (henceforth referred to as the perpendicular direction). Consequently, with the housing hole of the ball retainer, its inner diameter side and outer diameter side are linked in the perpendicular direction, and the ball member moves in the perpendicular direction inside the housing hole.
The ball receiver is provided on the outer assembly. The ball receiver contacts the ball member on its tapered surface. During operation, when the piston member moves to the lock position, the ball receiver cooperates with the ball members to connect the inner assembly and the outer assembly.
For the ball retainer, a plurality of flat springs are provided along the outer perimeter surface of the ball retainer excluding the housing holes. Particularly when the inner assembly and outer assembly are being disconnected, the ends of adjacent flat springs assist in preventing the loss of ball members and urge the ball members toward the inner diameter of the ball retainer.
Japanese Laid-Open Patent Number 4-63688 provides a robot hand tool linkage device wherein a plurality of flat springs are on the outer perimeter surface of the ball retainer. The loss of ball members from the ball retainer is prevented by these flat springs.
Unfortunately, according to the robot hand tool linkage device described above, a plurality of flat springs are required to prevent the loss of ball members by impelling the ball members toward the inner diameter of the ball retainer. As a further detriment, the above designs require a large number of parts, and the structure is detrimentally complex, leading to higher manufacturing costs.
Since ball members are used as joining members, there is point contact or line contact between the spherical surface of the ball member and the flat surface of the ball receiver. The actual contact surface area is detrimentally small resulting in adversely high contact surface pressure.
Additionally, since the structure has a plurality of ball members placed along the entire perimeter, the contact parts between the ball member and the ball receiver is present only intermittently along the entire perimeter, and the contact surface pressure of the locking mechanism, as a whole, is detrimentally high. This high contact surface pressure results in substantially shortened mechanical life and reduces reliability.
It is an object of the present invention to provide a tool linkage device for a robot hand which overcomes the drawbacks of the related art described above.
It is another object of the present invention to provide a robot hand tool linkage device that reliably prevents the loss of the joining member, reduces the number of parts, simplifies the structure and design, reduces contact pressure between operable parts, maintains low manufacturing costs, and increases the durability of the device while retaining operational effectiveness.
The present invention relates to a robot hand tool linkage device that is equipped with a master plate that is connected to the output part of a robot hand, a tool plate onto which a tool is connected, and a locking mechanism that releasably locks the master plate and tool plate.
In particular, with the robot hand tool linkage device of the present invention, the locking mechanism comprises: an actuation shaft that is supported by the master plate and is driven between a lock position and a release position by an air cylinder inside the master plate; a ring-shaped retainer that is affixed to the master plate and that surrounds an outer perimeter of an output part of the actuation shaft; a plurality of rod insertion holes that are formed in an inner perimeter wall of the retainer and are formed penetrating in a radial direction that is perpendicular to a sliding direction of the actuation shaft; a ring-shaped groove that is formed on the retainer on an outer perimeter side of the plurality of rod insertion holes and that is formed with the outer perimeter side open; a plurality of push rods that are attached movably in the plurality of rod insertion holes and that transfer the output of the actuation shaft radially outward; and a plurality of arc-shaped locking members that are attached in a manner allowing for sliding in a radial direction in the ring-shaped groove and that are in contact with or are coupled with the ends of the push rods.
With this robot hand tool linkage device, when connecting the tool plate and the master plate, after positioning the master plate and the tool plate and forming a temporary connection, an actuator shaft is moved to a lock position by an air cylinder. Thereupon, each push rod is pushed radially outward, and a plurality of arc-shaped locking members slides radially outward where it and joins with the tool plate. With this, the tool plate and the master plate are securely locked. When releasing the connection between the tool plate and the master plate, the actuator shaft is moved to a lock release position by the air cylinder. Thereupon, the plurality of arc-shaped locking members moves to a smaller radius, and each push rod moves radially inward. Afterwards, when the pin connections and the like between the tool plate and the master plate are released, the connection between the tool plate and the master plate is completely released.
Other preferred constructions for the present invention are described in the preferred embodiments of the present invention.